Two thousand participants in the 'Survival Zombie' roleplaying game invaded the streets of Collado Villaba near Madrid on Saturday, many dressed in full undead make-up and costumes.

The end of the world was nigh for those taking part in the 11pm-to-7.30am nightmare scenario. Players plunged into an imaginary universe where a virus had turned humans into shuffling undead monsters: the aim of the game was to get through the night without being touched and 'infected'.

Every would-be hero had to carry a passport, an identifying handkerchief and even fake cash to bribe other players.

The game is the brainchild of Diego de La Concepción, president of World Real Games, who started with a paintball range and worked up to organizing this ambitious roleplaying event.

According to Spanish daily El Mundo, keeping the game running smoothly requires 150 staff, most of them volunteers, who take charge of check-in, make-up, zombie horde control and zombie conversion. There are also professional actors to make the groans and screams more believable.

De la Concepción claims that the game gives a significant boost to the local economy.

"The town hall pays a minimum that's multiplied by a factor of fifteen in terms of the impact on bars and restaurants. Everything is sourced in local businesses, from t-shirts to theatre groups," he said.

The next game is scheduled to take place in Valencia in September. If you see someone eating human brains in the street, you may want to check the game's website before phoning the police...